1. Technical Field
The present invention relates to a lighting device transmitting a light emitted from a light source to a lighting section by using a light guide. In addition, it relates to an electro-optical device constituted by means of using the lighting device. Besides, it relates to an electronic apparatus constructed by using the electro-optical device.
2. Related Art
Recently, an electro-optical device such as a liquid crystal display device is widely used for electronic apparatuses such as cellular phone, PDA, IC recorder and the like. For example, in order to display a variety of information about an electronic apparatus with an image, the electro-optical device is used. Since this electro-optical device performs the display by controlling a light through the electric control, a lighting device is required as a source of light.
A lighting device used as an electro-optical device generally comprises a light guide formed by a translucent resin and a light source generating the light. LED (Light Emitting Diode), for example, is chiefly utilized for the light source. After the light emitted from LED is introduced into and passes through an internal part of the light guide, it is provided for the display in the electro-optical device as a plane light emitted from a light transmitting plane of the light guide.
LED, a light source, is generally mounted on a board with flexibility, called FPC (Flexible Printed Circuit) board. In addition, LED is provided so that an emitting plane faces with a light receiving plane of a light guide by connecting the FPC board to a frame having the light guide or itself.
As the above-mentioned lighting device, generally, there is provided the lighting device formed by the structure executing the positioning of LED for a light guide by engaging a notch provided in the edge part of the FPC board and a rib provided in a frame of the FPC board. (For example, see JP-A-2004-258236 FIG. 4, Page 5) Furthermore, there is also provided the lighting device with the structure implementing the positioning of LED for the light guide by connecting a pin for the positioning provided in a emitting plane of LED and a gullet for the positioning provided in a light receiving plane of the light guide. (For example, see JP-A-2001-330830 FIG. 2, Page 9)
However, the lighting device disclosed in JP-A-2004-258236 FIG. 4, Page 5, comprising: There is the possibility that LED is dislocated from a predetermined position for a light guide in case the size difference is shown between a notch of a notch provided in the FPC board and a position of a rib provided in a frame. In this case, there is a possibility that the brightness of the lighting device is dispersed. In addition, since the size difference is shown between the position of the notch and the position of the rib provided in the frame, it is the possibility that a gap appears between the light guide and LED. It is the possibility that due to the gap, the brightness of the light introduced into the light guide is lowered. Besides, in the lighting device disclosed in JP-A-2001-330830 FIG. 2, Page 9, there is a possibility that the brightness of the lighting device is dispersed since a special shape is formed on an emitting plane of LED.